Refractive index sensing based on scattering-mediated spectral shifts in polymer fiber gratings

Abstract Refractive index sensing using a fiber grating inscribed in a perfluorinated graded-index polymer optical fiber is experimentally demonstrated based on wavelength-domain interrogation of scattering-mediated spectral shifts. When liquids with different refractive indices are deposited onto the grating region, a systematic shift of a scattering-related dip wavelength is observed in the transmitted spectrum. The dip wavelength shifts monotonically toward longer wavelengths as the refractive index increases from 1.33 to 1.44, with a total shift of approximately 0.7 nm. These results demonstrate the feasibility of refractive index sensing using polymer fiber gratings through wavelength-domain analysis of scattering-mediated spectral shifts.